Dentist&#39;s furnace



mmh s? @922:2 1,620,179

- y Fe. M. WHITE DENTIST S FURNACE Y Filed Ami. 2, 1926 gf Y f@ Patented Mar. 8, 1927.

UNITED STATES l,62ti,l79

ROY M. WHITE, OF RIVERSIDE, CALIFORNIA.

DENTIST S FURNACE.

Application :filed August 2, 1925.

This invention relates to a furnace which is intended t0 be particularly useful to dentists in producing small molded parts for use in dentistry. It is a customary practice to provide a mold for such a part and to produce a wax model of the part in this mold. In other words, a replica of the part to be molded is formed in wax. This replica is then embedded in an investment of plaster of Paris or similar mate ial in a molding flask. This flask is of very simple construction and usually consists of a wide ring or tube of copper or brass. The wax replica is held in the interior of this ring embedded in the plasterl of Paris. After the investment is sufficiently hard, the flask is placed in a furnace in an inverted position, and subjected to suflcient heat to melt the wax, which then runs out of the flask through a duct.

It is desirable to effect the melting of the wax quickly, without subjecting the investment to the heat for a sufficient time to bake it. This is .desirable because after the dental part has been molded in the flask, it facilitates the removal from the embedding plaster of Paris.

In order to accomplish these effects, it is desirable that a furnace for this purpose should be capable of subjecting the flask to a relatively high temperature for a short time. It is also frequently necessary for the dentist to perform soldering operations upon dental parts which he has molded.

The general object of this invention is to provide a furnace of simple construction which can be used for subjecting such a molding flask to a high temperature, and provided with improved means for regulating the admission of air to the furnace; also to provide such a furnace with means for supporting parts at a position in the furnace where they can be heatedto a high teinperature for performing such soldering operations; also to provide a specialconstruction of the furnace which will enable the wax which runs out of the flask to be carried out of the furnace.

Further objects of the invention will appear hereinafter.

The invention consists in the novel parts and combination of parts to be described hereinafter, all of which contribute to produce an eliicient dentists furnace.

Serial No. 126,461.

A preferred embodiment of the invention is described in the following. specification,

while the broad scope of the invention is pointed out in the appended claims.

In the drawing:

Figure l is .a side elevation of the coniplete apparatus.

Figure 2 is a plan of the apparatus with the legs and hood removed.

Figure 3 is a vertical section through the apparatus, certain parts being broken away.

Fgiure 4 is a vertical section through the flask which may be used with the apparatus.

Inpracticing the invention, I provide a shell which operates as a fire pot; I also provide a plurality of burners mounted in the shell in a position such that the flames from the burners converge upon a point within the shell. liVithin the shell, I provide a platen for supporting a molding flask, upon which the flames impinge.

In the embodiment of the invention illustrated, l represents a shell which may be of rectangular or cylindrical form. This shell.

is preferably constructed of metal and has a wall of subs lantial thickness, so as to enable it to yabsorb considerable heat.

The shell is supported on a frame 2, preferably constructed of gas pipe and compris-V ing a plurality of vertical pipes 3 which operate as legs for the frame, the upper ends of these pipes being provided with burners l which extend into the interior of the shell and preferably through the wall of ther-aine at a point slightly below the, middle of the shell. The lower end of the frameaQ is formed of a spider or cross 5 of pipes connecting to a central lf-connection G, and the ends of the cross pipes connect to the vertical pipes 3. The spider 5 is supplied with through a gas pipe 7 which attaches to a T- connection S connecting to the spider on one side and connecting with one of the legs or vertical pipes 3 on its upper side. This Vpipe is indicated specifically by the numeral 3.

Within the shell l, I provide a platen Si for supporting a molding flask lt), such as illustrated in Fig. 4. This platen may be in the form of a grating composed of narrow flat bars. Any suitable means may be provided for supporting the platen and regulating the height of the saine within the shell.l For this purpose, I prefer to attach the platen to the upper end of a stein 11, and this stem is supported by means guided on the frame 2. In the present instance, I accomplish this by means of a bracket 12 in the form of a short arm having a guide shoe 13 in the form of a T-connection` which slides on the vertical pipe 3a. At its inner end, this bracket inclu-des a T-connection 14, into the upper end of which the stem l1 is threaded. The shoe or T-connection 13 is provided with a set screw 15 carrying a hand-.wheel 16 for operating the same. ylhis hand-wheel enables the set screw to be screwed tight against the side of the vertical pipe 3a to hold the platen at any height desired within the shell. A

In Fig. 3, the dotted lines indicate 'the operating posit-ion of the platen, .at which time it will `operate to support the. platen on the axis of the shell and in a position such that the flames 17 from the different burners will impinge upon it. In the present instance, there are four of these burners and they are all disposed radially about the axis of the shell.

If desired, means may be provided for regulating the admission of air through the lower end of the shell. For this purpose, I prefer to provide a damper consisting of two discs 18 which are superposed upon each other and provided with openings 19 which may align more or less, if desired, to enable a large quantity of air to be admitted or to substantially shutV otl flow of air if all the openings are closed.

The platen 9 and the dises 18 may be secured on the stem 11 by providing a thread on `the stem; two clamping nuts in the form of two discs 20 may be mounted on this thread to clamp the platen between them. The upper disc 18 may also have a. thread connectionon this stem 11 and the lower disc 1S is loose on the stem but held against the under side of the upper disc by a nut or threaded disc 2l. In this way, the lower disc will be held so that it can be rotated as desired for adjusting the draft through the aligning openings 19.

The flask 10 is of simple form and usually consists of a wide ring or short tube 22 ofibrass, copper or similar highly conductive metal. In using this flask, the article 23 which is to be molded is embedded within the ring 22 in plug 24e of plaster of Paris or similar material, one end of said plug haiL ing a conical or 'funnel-shaped mouth 25 communicating with a duct 26 which leads down to the article 23, which is formed of wax and which is a replica of the article to be cast. After embeddingl the replica 23 in the flask in this way, the flask is then placed on the platen 9 in an inverted position, that is to say, with the duct 25 disposed downwardly. The burners 4t are then lighted and the temperature of the flask is rapidly raised Vby the llames which impinge upon the ring 22. This quickly melts the wax, which runs down the duct- 26.

In order to enable this wai; to run out of the furnace, the stem 11 is preferably of tubular form so that when the duct 26 is placed over it, it will permit the wax to fall through it and also through the T-connection let at the lower end of the stem. After the wax has been run out of the mold in this way, the flask 10 may be supported on a platen or grating 2T at the upper end of the Shell and .filled with molten metal to form the desired casting. This upper platen may be supported on small Z-brackets 28.

In order to asist in holding the plug of plaster of Paris or other composition withT in the ring 22, the inner side of the wall of the ring has a projection 29 which prof jects into the interior of the ring.

At their lower ends, the vertical pipes 3 are provided with air inlets 30 so that4 all of the burners practically operate as Bunsen burners.

If it is desired to develop an unusually high temperature within the shell, I may provide a hood 31 which is received removably on the upper end of the casing. This hood may be simply of conical form so as to fit down over the upper end' of the casing, and may be provided With a. handle 32 for lifting it. If it is desired to carry off the gases of con'ibustion, this hood may be provided with a small stack 33 which operates like a stove-pipe to carry the gases of combustion up to an elbow i which can be di-. rected `out'of ay window.

The upper grating or platen 2T not only l til) operates as a. convenient support for the flask when it is being filled during the casting operation, but also may be used by the dentist with the flames lighted to heat parts in performing any other mechanical operations.

It is understood that the embodiment of the invention described herein is only one of the many embodiments this invention may take, and I do not wish to be limited in the practice of the invention, nor in the claims, to the particular embodiment set forth.

I claim 1. In a dentists furnace, the combination of a shell, a plurality of burners mounted in the shell in a position such that the flames from the burners converge upon a point within the shell, and a platen for supportingI a molding flask with means 'for supporting` the platen within the shell.

2. In a dentists furnace, the combination of a shell, a plurality of burners mounted in the wall of the shell in a position so that the flames from the burners converge upon a point within the shell, a platen mounted within the shell for sup` porting a molding flask within the same, means for supporting the platen at different levels within the shell, and a damper at the lower end of t-he shell for regulating the admission of air.

V3. In a dentists furnace, the combinat-ion of a shell, a plurality of burners disposed in a substantially radial position around the axis of the shell, a stem extending up into the shell from below, a. grating carried by the upper end of the stem for supporting a molding flask between the burners, a disc carried on the stem below the grating with means for adjusting the same toregulate the amount o-f air admitted past the disc, and means for holding the stem in different positions to regulate the height of the grating within the shell and to lower the grating so as to remove the molding flask from the shell when below it.

4. In a dentists furnace, the combination of a substantially cylindrical shell, a. plurality of burners extending through the shell from the outer side and disposed radially about the axis of' the shell, said burners having substantially vertical supply pipes constituting a frame to support the shell, a bracket slidably mounted on the frame, with means for holding the same at different elevations, a stem carried by the bracket extending up into the shell, and a grating carried by the stem within the shell for supporting a molding flask between the burners.

5. In a dentists furnace, the combination of a substantially cylindrical shell, a plu-l rality of burners extending through the shell from the outer side and disposed radially about the axis of the shell, said burners hating substantially vertical supply pipes constituting a frame to support the shell, a bracket slidably mounted on the frame, with means for holding the same at different elevations, a. stem carried by the bracket extending up into the shell a grating carried by the stem within the shell for supporting a. molding flask between the burners, and a disc adjustably mounted on the stem for regulating the admission of air through the lower end of the shell.

G. In a dentists furnace, the combination of a substantially cylindrical shell, a frame formed of pipes and including substantially upright pipes with burners secured to their upper ends and projecting through the wall of the shell, a connect-ion for supplying gas to the said frame, a bracket slidably mounted on said frame with means for securing the same adjustably thereto, apstem extending up from the bracket through the lower end of the shell, and a platen carried by the upper end of the stem for supporting a molding flask between the burners.

7. In a dentists furnace, the combination. of a shell open at its lower end and at its upper end, a plurality of burners extending through the wall of the shell, a platen within the shell for supporting a molding flask between the burners, means for holding the platen at different adjusted posit-ions within the shell, and a second platen with means for removably supporting the same within the shell adjacent the upper end thereof. y

8. In a dentists furnace, the combination of a substantially cylindrical shell, a frame formed of gas-pipe supporting the shell, said frame including substantially vertical pipes with gas jets at the upper ends thereof extending through the wall of the shell and disposed substantially radially around the axis of the shell, a platen for supporting a molding flask disposed within the lower end of the shell, with means for adjustably supporting the same, and a substantially conical hood constructed to seat on the. upper end of the shell.

9. In a dentists furnace, the combination of a shell, a tubular stem extending up into the shell, a. platen supported on the stem for supporting a molding flask within the same, and burner means extending into the interior of the shell for projecting a flame upon the molding flask.

l0. In a dentists furnace, the combination of a shell, a tubular stem extending up into the shell, a platen supported on the stem for supporting a molding flask within the same, burnermeans extending into the interior of the shell for projecting a flame upon the molding flask, and means carried on the stem below the platen for regulating the admission of air to the lower end of the shell.

l1. In a dentists furnace, the combination of a shell, a stem extending up into the interior of the shell, a platen carried on the upper end of the stem for supporting a molding flask, a burner device extending into the interior of the shell for projecting a flame onto the molding flask, and a pair of perforated discs carried on the stem below the platen, the perfora-tions of said discs being disposed so as toregister more or less to regulate the admission of air to the lower end of the shell.

12. In a dentists furnace, the combination of a substantially cylindrical shell, a. p1urality of burners extending through the shell from the outer side and disposed radially about the axis of the shell, said burners having substantially vertical supply pipes constituting a frame -to support the shell, a bracket slidably mounted on the frame, with means for holding the same at different elevations, a stem carried by the bracket extending up into the shell, a platen carried by the stem within the shell for supporting a molding flask between the burners, al disc adjustably mounted on the stein for regulating the admission of airrthrough the lower llt end of the shell, and a second platen with ineans for removably supporting the saine Y within the shell adjacent the upper end thereof.

13. In a dentists furnace, the combination of a substantially cylindrical shell, a plurality oft' burners extending through the shell from the outer side and disposed radially about the axis of the shell5 said burners having substantially Vertical supply pipes .constituting a frame to support the shell, a bracket slidably mounted on the frame, with means for vholding the saine at different elevations, a stein carried by the bracket ing the admission of air through the lower end of the shell, a second platen with means for removably supporting the saine Within the shell adjacent the upper end thereof, and a substantially conical hood constructed to seat on the upper end of the shell.

Signed at Riverside, California, this 2G day of July, 1926.

ROY M. WHrT'E. 

